The present invention relates generally to the field of fastening devices, and more particularly to secured fastening devices. Still more particularly, it relates to secured fastening devices sealed against environmental corrosion and degradation.
Many machines or devices often are assembled from elements that must be fastened together to be operable. Such fastening sometimes must be other than permanent and capable of subsequent disassembly to allow for maintenance, repair, and replacement of worn or broken components. In such instances, some modes of fastening (e.g., welding or gluing) are undesirable since they form a permanent bond. One preferred fastening method that permits subsequent disassembly is to use a threaded fastener, such as a bolt or a stud, joined with a matching threaded nut. A rigid connection thus can be achieved, to be dismantled later as necessary.
Employing removable fasteners to permit subsequent dismantling of an assembly, however, creates a security problem. Frequently, whatever is fastened together is of value and, hence, attractive to thieves and vandals. If any valuable element of the assembly is readily removable and transportable, the danger of theft and loss becomes more acute. In particular, items which often remain outdoors and/or within accessible but unsecured areas are those most likely to be subject to vandalism and theft. A variety of commonly-owned articles fall in such a category of loss-prone items. Outboard motors fastened to boats, motorcycle parts, furniture, lighting fixtures, statuary, and the like, all are examples of items that might be fastened in place and are probable candidates for theft.
One solution to the hazard of theft has been to provide secured, lockable fastening means. Prior art devices exist that allow locking or otherwise securing a fastener to prevent unauthorized removal of that fastener. One prior art apparatus, for example, has found application in securing propellers to motorboat engines. This apparatus includes an elongated nut attached to a threaded bolt to secure the propeller to the motor shaft. A cotter pin penetrates the nut and the bolt to prevent accidental rotation of the bolt and resultant loss of the propeller. A set screw in the body of the nut further impedes unintended rotation of the nut. A lockable, sleeve-like metal housing slides over the assemblage after the nut, set screw, and cotter pin are installed. When the housing seats and is locked in place, it partly covers the nut, blocking access to and thereby preventing removal of the cotter pin. The housing remains free to rotate around the nut, even while locked to the nut. The housing thus deters a would-be thief in three ways. First, it prevents removal of the cotter pin, thereby preventing rotation of the nut. Secondly, it protects and shields the set screw that holds the nut in place. Lastly, it precludes application of torque to the body of the nut; rotating the housing will not rotate or affect the position of the nut.
Prior art devices are known, then, for securing a nut and bolt assembly, or other fastener, against unauthorized casual--or even determined--removal. Certain environments and extended use or exposure, however, can drastically reduce the widespread applicability of such devices. Corrosion is always a problem with removable fasteners such as threaded nuts and bolts. Corrosion of the threads can make removal of the nut difficult or impossible. Corrosion, moreover, can render a lock housing, a lock cylinder, and other intricate moving parts inoperative and useless. Corrosion of locking mechanisms securing fasteners thus only worsens the effects of the environment, obstructing or precluding disassembly of fastened components when such disassembly is required. More severe operating environments hasten and magnify the severity of corrosion and environmental degradation.
It can be seen, then, that a need exists for fasteners that can be secured against unauthorized breakage and tampering. Devices are existent in the prior art that accomplish the limited objective of maintaining security for fasteners. The prior art devices, however, suffer from vulnerability to corrosion and environmental exposure, a vulnerability that reduces the net value and shortens the operating life of such prior art devices. A continued need exists for fasteners that are not only secured, but can be protected against the elements to enhance and extend the economic advantage and the life of such secured fasteners.